The mitigation efforts of Berkeley Earth are aimed at objective analysis of proposed programs to limit or reduce greenhouse missions. We emphasis the need to achieve clean energy within a realistic and affordable framework in the developing world, where emissions are growing most rapidly. Natural gas, if produced cleanly, might be a practical and achievable bridging technology while we bring down the price of renewables to the point where they can be competitive with coal in the developing world. The Berkeley Earth vision for greenhouse gas mitigation centers on expediting the Chinese transition away from coal to natural gas, but only if it can be done in a clean way. In particular, we need to guarantee that fugitive emissions (leaked natural gas) are kept below an acceptable level, perhaps 1%.